Add branch matching (#2329)

.github/workflows/build_and_test.yaml

@@ -15,6 +15,7 @@ jobs:
         with:
             config: ${{ (github.event.pull_request.base.ref || github.ref_name) == 'develop' && 'element.io/nightly' || 'element.io/release' }}
             version: ${{ (github.event.pull_request.base.ref || github.ref_name) == 'develop' && 'develop' || '' }}
+            branch-matching: true
 
     windows:
         needs: fetch

.github/workflows/build_prepare.yaml

@@ -20,6 +20,11 @@ on:
                 required: false
                 default: false
                 description: "Whether the build should be deployed to production"
+            branch-matching:
+                type: boolean
+                required: false
+                default: false
+                description: "Whether the branch name should be matched to find the element-web commit"
         secrets:
             # Required if `nightly` is set
             CF_R2_ACCESS_KEY_ID:
@@ -59,7 +64,25 @@ jobs:
             - name: Install Deps
               run: "yarn install --frozen-lockfile"
 
-            - name: Fetch Element Web
+            - name: Fetch Element Web (matching branch)
+              id: branch-matching
+              if: inputs.branch-matching
+              continue-on-error: true
+              run: |
+                  scripts/branch-match.sh
+                  cp "$CONFIG_DIR/config.json" element-web/
+                  yarn --cwd element-web install --frozen-lockfile
+                  yarn --cwd element-web run build
+                  mv element-web/webapp .
+                  yarn asar-webapp
+              env:
+                  # These must be set for branch-match.sh to get the right branch
+                  REPOSITORY: ${{ github.repository }}
+                  PR_NUMBER: ${{ github.event.pull_request.number }}
+                  CONFIG_DIR: ${{ inputs.config }}
+
+            - name: Fetch Element Web (${{ inputs.version }})
+              if: steps.branch-matching.outcome == 'failure' || steps.branch-matching.outcome == 'skipped'
               run: yarn run fetch --noverify -d ${{ inputs.config }} ${{ inputs.version }}
 
             # We split this out to save the build_* scripts having to do it to make use of `hashFiles` in the cache action

scripts/branch-match.sh

@@ -0,0 +1,48 @@
+#!/bin/bash
+
+# Script for downloading a branch of element-web matching the branch a PR is contributed from
+
+set -x
+
+deforg="element-hq"
+defrepo="element-web"
+
+# The PR_NUMBER variable must be set explicitly.
+default_org_repo=${GITHUB_REPOSITORY:-"$deforg/$defrepo"}
+PR_ORG=${PR_ORG:-${default_org_repo%%/*}}
+PR_REPO=${PR_REPO:-${default_org_repo##*/}}
+
+# A function that clones a branch of a repo based on the org, repo and branch
+clone() {
+    org=$1
+    repo=$2
+    branch=$3
+    if [ -n "$branch" ]
+    then
+        echo "Trying to use $org/$repo#$branch"
+        # Disable auth prompts: https://serverfault.com/a/665959
+        GIT_TERMINAL_PROMPT=0 git clone https://github.com/$org/$repo.git $repo --branch "$branch" --depth 1 && exit 0
+    fi
+}
+
+echo "Getting info about a PR with number $PR_NUMBER"
+apiEndpoint="https://api.github.com/repos/$PR_ORG/$PR_REPO/pulls/$PR_NUMBER"
+head=$(curl "$apiEndpoint" | jq -r '.head.label')
+
+# for forks, $head will be in the format "fork:branch", so we split it by ":"
+# into an array. On non-forks, this has the effect of splitting into a single
+# element array given ":" shouldn't appear in the head - it'll just be the
+# branch name. Based on the results, we clone.
+BRANCH_ARRAY=(${head//:/ })
+TRY_ORG=$deforg
+TRY_BRANCH=${BRANCH_ARRAY[0]}
+if [[ "$head" == *":"* ]]; then
+    # ... but only match that fork if it's a real fork
+    if [ "${BRANCH_ARRAY[0]}" != "$PR_ORG" ]; then
+        TRY_ORG=${BRANCH_ARRAY[0]}
+    fi
+    TRY_BRANCH=${BRANCH_ARRAY[1]}
+fi
+clone "$TRY_ORG" "$defrepo" "$TRY_BRANCH"
+
+exit 1

scripts/fetchdep.sh

@@ -1,41 +0,0 @@
-#!/bin/bash
-
-set -x
-
-deforg="$1"
-defrepo="$2"
-defbranch="$3"
-
-[ -z "$defbranch" ] && defbranch="develop"
-
-rm -r "$defrepo" || true
-
-clone() {
-    org=$1
-    repo=$2
-    branch=$3
-    if [ -n "$branch" ]
-    then
-        echo "Trying to use $org/$repo#$branch"
-        # Disable auth prompts: https://serverfault.com/a/665959
-        GIT_TERMINAL_PROMPT=0 git clone https://github.com/$org/$repo.git $repo --branch "$branch" --depth 1 && exit 0
-    fi
-}
-
-# Try the PR author's branch in case it exists on the deps as well.
-# If BUILDKITE_BRANCH is set, it will contain either:
-#   * "branch" when the author's branch and target branch are in the same repo
-#   * "author:branch" when the author's branch is in their fork
-# We can split on `:` into an array to check.
-BUILDKITE_BRANCH_ARRAY=(${BUILDKITE_BRANCH//:/ })
-if [[ "${#BUILDKITE_BRANCH_ARRAY[@]}" == "1" ]]; then
-    clone $deforg $defrepo $BUILDKITE_BRANCH
-elif [[ "${#BUILDKITE_BRANCH_ARRAY[@]}" == "2" ]]; then
-    clone ${BUILDKITE_BRANCH_ARRAY[0]} $defrepo ${BUILDKITE_BRANCH_ARRAY[1]}
-fi
-# Try the target branch of the push or PR.
-clone $deforg $defrepo $BUILDKITE_PULL_REQUEST_BASE_BRANCH
-# Try the current branch from Jenkins.
-clone $deforg $defrepo `"echo $GIT_BRANCH" | sed -e 's/^origin\///'`
-# Use the default branch as the last resort.
-clone $deforg $defrepo $defbranch